The invention relates to a device for cleaning electrified contact (or third) rail insulators for rail rapid transit systems to prevent arcing and smoke. There may be one or two contact rails. The contact rail typically carries over 700 volts and sits on porcelain or fiberglass composite insulators. The contact rail often has a safety cover that limits access to the insulators. Anchors, brackets and cables also limit access to the insulators. Cleaning with hand brushes, cleaning pads, or pressure washing (and blow drying with compressed air to prevent wet surfaces from conducting electricity) is slow, costly, and not fully effective.
The problem is that electrically conducting particulates and dirt adhere to the insulators. Normal maintenance of the tracks includes rail grinding that generates a significant amount of iron particulates that coat the insulators. Rust and brake shoe particles also coat the insulators. Snow and highway deicing salt can be thrown by snow plows from a highway running next to the track, or salted snow can melt and the salt water can drip down from a road above the track, and coat the insulators. Sea water can drip into a rail tunnel under the sea and the salt can coat and short out the insulators. The insulators eventually fail and arc, producing smoke and flame. If the insulator is made of fiberglass, it can burn. Porcelain insulators can become red hot and melt. The hot insulators can cause wood ties to catch on fire. The reduced support to the running rails due to a burnt out tie, may cause a derailment of the railcar and train with catastrophic results. The contact rail cover guard is typically made of fiberglass, and it can also burn. A failed insulator can cause the electric supply cable to overheat and cause the plastic cable covering to smoke and burn. When there is a smell of smoke, the system may have to be shut down until an investigation shows that there is no danger of fire. Note that a 10-minute smoke incident delay on one track can tie down much of an entire city rail transit network for 40 minutes or more.
When smoke is reported or arcing is seen, the policy of one transit authority was to stop rail traffic. The local Fire Department was called. It inspected the location where smoke was reported. If an arcing insulator was discovered, it was removed immediately with a sledgehammer and replaced at night when the system was closed to the public. The loss of income to the rail system and lost time for the passengers was substantial. Rail transit systems routinely replace thousands of burnt out insulators every year at considerable cost. Cleaning insulators is especially difficult and costly inside tunnels where there is no rain to wash away dust and nowhere for combustible debris and smoke to go.
Some transit systems and their electric switchgear are so old that it is difficult to turn the power back on after turning it off. It would be advantageous to clean the insulators with the power on. If the electricity is not cut off, tap water cannot be used for cleaning the insulators because of the danger of electric shorts. Also, harsh and abrasive cleaners and cleaning media cannot be used as they may damage the ceramic or fiberglass composite insulators, or cause corrosion and malfunction of switches, sensors, and metal components. Most jurisdictions ban the use of cleaning chemicals because of environmental and health concerns.
The insulator cleaning device of the invention is attached to a service vehicle that travels on the tracks and quickly cleans the insulators as it goes along. The insulator cleaning device will improve the safety and security of the rail rapid transit system. After the recent attacks on the Pentagon and the World Trade Center, people are concerned about their safety. Smoke and electric arcing from dirty insulators and delays in dark tunnels may cause fear and scare people away from using rail rapid transit. Diversion to personal modes of transport will cause traffic jams and delays, and hurt economic development. The cleaning device of the invention will enhance the public perception of a safe and secure rail transit system and support economic development.